资源环境科技发展态势分析平台

We analyze the results of the gravity wave (GW)-resolving, high-resolution Kuhlungsborn Mechanistic general Circulation Model in July at McMurdo Station (166.69 degrees E and 77.84 degrees S), where strong downslope eastward winds create strong mountain wave (MW) events. These MWs have horizontal wavelengths of (H)similar or equal to 230km, propagate to z approximate to 40-60km, and can have upward phases in time if the eastward wind accelerates in time. Additionally, inertia-GWs (IGWs) with (H)approximate to 500-800km and ground-based periods of (r)approximate to 5-6hr are generated in the troposphere from unbalanced, large-scale flow. The density-scaled GW amplitudes are approximate to 10 times smaller at z approximate to 80-100km than at z < 50km because of severe wave dissipation. Fishbone structures are seen at z approximate to 30-60km with upward (downward) phases in time below (above) the knee at z(knee). We horizontally filter the perturbations to isolate the GWs in a fishbone structure for a particular MW event. We find that these GWs have strikingly similar parameters below and above z(knee)=46km, with ground-based horizontal phase speeds of c(H)approximate to 40-60m/s, (r)approximate to 9-10hr, (H)approximate to 1,600-2,050km, vertical wavelengths of (z)approximate to 18-25km, and azimuths of ?=145 degrees -151 degrees east of north. We show that these are secondary GWs excited by a body force at z(knee) created by MW dissipation approximately 400km northwest of McMurdo 2.5hr earlier and that the secondary GW scales and propagation directions are consistent with this force. Importantly, we show that most of the GWs at z > 70km are secondary GWs not primary GWs from the troposphere.